The Power Stone

Indestructible, equip {2}
When the Power Stone enters the battlefield,
target creature gets +2/+2 until end of turn.
Equipped creature gets +2/+2 and has {1}{r}:
put a double strike, menace, or trample counter
on target creature. Activate only as a sorcery.
At the beginning of your end step, exile
equipped creature if its non-legendary.